PHOENIX (AP) Kevin Towers appeared to have a tenuous hold on his job as Arizona's general manager when the Diamondbacks hired Tony La Russa to run their baseball operations.

Though the Hall of Fame manager said he was going to evaluate the entire organization, it seemed only to be a matter of time before the reins were taken away from Towers.

The change came on Friday, when Arizona fired Towers in the midst of a third straight disappointing season, less than four months after La Russa was named chief baseball officer.

''Over the past three months, I have had the opportunity to evaluate all aspects of our baseball operations and have decided to restructure our staff in order to improve our decision-making process,'' La Russa said. ''I have the utmost respect for Kevin and a friendship with him that dates back many years which has allowed me to appreciate his talents and experience.''

Towers was hired in 2010 after 14 seasons as the San Diego Padres' general manager. He had almost immediate success, pulling off all the right moves to help Arizona win the 2011 NL West crown, its first division title since 2007.

Since then, Towers' moves haven't paid off quite as well and the Diamondbacks have suffered, following a pair of .500 seasons with a nosedive this year.

''You can see it coming but you don't want to believe it,'' catcher Miguel Montero said. ''It's really sad that it's come to this.''

Plagued by injuries and subpar seasons from players it had counted on, Arizona lost 22 of its first 30 games to plummet into last place and never really recovered, entering Friday night's game at 59-81 - 11 1-2 games behind the first-place Los Angeles Dodgers.

''It's a bummer,'' first baseman Mark Trumbo said. ''You never want to see anyone relieved of their role in the organization, especially when it comes as a result of the team underperforming.''

Towers said La Russa told him he wanted to restructure the front office a couple of weeks ago and was offered another position within the organization. Towers plans to stay with the organization at least until the Diamondbacks hire a new GM and decide on his future once he knows who the new person will be.

La Russa said current agent Dave Stewart, a pitcher under La Russa with the Oakland Athletics, and St. Louis farm director Gary LaRocque are on Arizona's list of potential replacements. He also has talked to Diamondbacks scouting director Ray Montgomery, and asked permission to speak with New York Yankees assistant GM Billy Eppler and Los Angeles Angels scouting director Hal Morris.

''When I took this job in 2010, we wanted to win a World Series and we won very early here, set high standards for ourselves,'' Towers said. ''Since 2011, we haven't met the standards that we hoped, ownership had hoped for and our fan base hoped for, and ultimately I'm going to be held accountable for that.''

With manager Kirk Gibson at the helm, Arizona had a dramatic turnaround in 2011, winning 94 games and the NL West after losing 97 games the season before.

The success didn't continue.

Arizona went 81-81 the next two seasons despite a slew of moves by Towers and took another step backward this season after Gibson and Towers were given contract extensions.

''I look at K.T. and the thing that comes to my mind is how much better the organization is right now than we he arrived,'' Gibson said. ''He's done a great job.''

Injuries were a big part of the fall this season.

The Diamondbacks lost their No. 1 starter and setup man before the season even started, when Patrick Corbin and David Hernandez underwent Tommy John surgery. Trumbo, the team's key offseason acquisition, was tied for the NL lead in homers and second in RBIs, but went down with a stress fracture in his foot less than a month into the season.

Outfielder A.J. Pollock also missed significant time with a broken hand and All-Star first baseman Paul Goldschmidt was lost for the season last month with a broken hand.

''Wish we could have stayed healthy and enjoyed success year after year, but this season was a very trying year and when you don't meet expectations, things like this happen - and I know that,'' Towers said.

Even before the injuries struck, the Diamondbacks labored after a series of deals by Towers didn't pan out.

The big trade under Towers came before the 2013 season, when the Diamondbacks sent outfielder Justin Upton to the Braves for top pitching prospect Randall Delgado and three minor leaguers. Upton has continued to produce in Atlanta while the players Arizona got in return have yet to have much of an impact.

With the team out of contention, Towers and the Diamondbacks began dismantling the team around the trade deadline, pulling off deals that sent right-hander Brandon McCarthy, third baseman Martin Prado - the key cog in the Upton trade - and outfielder Gerardo Parra out of the desert.